Gallery: Cockroach feeding contraptions

by Mike

Cockroaches are disgusting. The presence of roaches indicates squalid and germ-ridden conditions. However… do the roaches themselves contribute to the pestilence? Or are they merely a symptom? Or perhaps they are actually beneficial, as they might be able to destroy the germs in their digestive tract.

This is the sort of question that scientists needed to answer. Dr. Stanley Wedberg (1913-2003) of the University of Connecticut created an optimal system for such studies. The cockroach would be immobilized on a block of paraffin in what looks like a comfortable reclining position. This was suited for controlling its food intake to contain known amounts of bacteria, and monitoring its excretions to see how much bacteria remained.

Published in 1947, his system was based on one demonstrated a year earlier by Hubert Frings, a postdoc at Edgewood Arsenal in Maryland. What?

Yes, Edgewood Arsenal, now part of the Aberdeen Proving Grounds, was basically the US Army’s chemical plant, and included a Medical Research Laboratory, which in turn included a division of entomology and insect physiology for some reason. Hubert Frings’s mentor was the head of entomology, Dr. Leigh Chadwick.

Anyway, Frings (who was later quoted in Sports Illustrated on the subject of how to keep birds away from rocket sleds) was using fixed feeding rigs to get insects to ingest chemicals, to measure toxicity. In the paper that demonstrated the cockroach apparatus, his aims were even less sinister, basically looking at which salt solutions cockroaches prefer to drink, and figuring out how high of a concentration is necessary for roaches to prefer sucrose to water.

Wedberg improved the mechanism by putting the roach on its back, which reduced regurgitation and made it more comfortable (yes, both papers use the word “comfort” with regard to how the roach feels). And just as significantly, he decided to use a different roach species, one that was bigger (meaning food and excreta could be measured more accurately), more docile, and had a broad, flat body type well suited for attaching to a block of paraffin.

Wedberg’s choice of Blaberus cranifer as the experimental model cockroach did not catch on, but his technique did, and therefore many subsequent papers just referred to Wedberg and Clarke (1947) or Wedberg, Brandt and Helmboldt (1949) instead of including their own pictures of their own roach restraint systems. But several scientists did seek to show the reader what their apparatus looked like.

Here are a few such pictures. There are probably a lot more in the hardcore entomology journals (J Med Entomol, J Econ Entomol) whose archives I can’t access.